Is there any need for trastuzumab after surgery if you received trastuzumab before surgery?

This paper studied the effect of adjuvant therapy (treatment given after surgery) in patients who had a complete response to therapy with trastuzumab (Herceptin) before surgery. 

Neoadjuvant systemic therapy is treatment used to decrease the size of the tumour before surgery. An example of treatment includes trastuzumab, which is used to treat breast cancer that is human epidermal growth factor receptor 2 (HER2) positive (presence of HER2). By treating cancer with trastuzumab and surgery, the aim is to achieve a complete response (disappearance of signs and symptoms of cancer). It is thought that also administering trastuzumab following surgery may increase the likelihood of achieving a complete response.  

The authors aimed to evaluate whether administering trastuzumab after as well as before surgery has any impact on response.

All patients received with trastuzumb before surgery. After surgery, 81% of patients received trastuzumab while 19% did not. Overall, 35% of patients achieved a complete response. Of patients achieving a complete response, 31% received trastuzumab after surgery. Of patients who did not achieve a complete response, 62% received trastuzumab after surgery.

After an average follow-up of 45 months, 6.5% of patients had died and 10.4% of patients had a recurrence (return of cancer). The overall survival was 91% for patients who did not receive trastuzumab after surgery and 93% for patients who received did receive trastuzumab after surgery.  At 5 years,  92% of patients who did not receive trastuzumab after surgery were recurrence-free.  At 5 years, 84% for patients who received trastuzumab after surgery were recurrence-free. Among patients achieving complete response, trastuzumab after surgery did not further improve overall survival or relapse-free survival (period without cancer returning).

When various factors were considered, there was no association between trastuzumab after surgery and complete response on overall survival.

Patients who achieved a complete response had a decreased risk of death and recurrence. 

The authors concluded that patients who achieved a complete response after receiving trastuzumab before surgery had excellent outcome whether or not they received trastuzumab after surgery.

There was a small number of patients studied.